feat: support prewhere, finish test for django<4.2

Author: jayvynl

clickhouse_backend/__init__.py

@@ -1,5 +1,5 @@
 from clickhouse_backend.utils.version import get_version
 
-VERSION = (1, 1, 7, "final", 0)
+VERSION = (1, 2, 0, "final", 0)
 
 __version__ = get_version(VERSION)

clickhouse_backend/models/sql/compiler.py

@@ -85,15 +85,7 @@ def pre_sql_setup(self, with_col_aliases=False):
                     must_group_by=self.query.group_by is not None
                 )
             else:
-                (
-                    self.prewhere,
-                    prehaving,
-                    prequalify,
-                ) = (
-                    None,
-                    None,
-                    None,
-                )
+                self.prewhere, prehaving, prequalify = None, None, None
             # Check before ClickHouse complain.
             # DB::Exception: Window function is found in PREWHERE in query. (ILLEGAL_AGGREGATION)
             if prequalify:
@@ -103,7 +95,10 @@ def pre_sql_setup(self, with_col_aliases=False):
         else:
             self.setup_query()
             self.where, self.having = self.query.where.split_having()
-            self.prewhere, prehaving = self.query.where.split_having()
+            if isinstance(self.query, Query):
+                self.prewhere, prehaving = self.query.prewhere.split_having()
+            else:
+                self.prewhere, prehaving = None, None
         # Check before ClickHouse complain.
         # DB::Exception: Aggregate function is found in PREWHERE in query. (ILLEGAL_AGGREGATION)
         if prehaving:

tests/clickhouse_queries/tests.py

@@ -3,6 +3,8 @@
 from django.db.models.functions import Rank
 from django.test import TestCase
 
+from clickhouse_backend import compat
+
 from . import models
 
 
@@ -33,12 +35,12 @@ def test_prewhere(self):
         self.assertEqual(qs[0].name, "a1")
 
     def test_prewhere_fk(self):
-        self.assertQuerySetEqual(
+        b1, b2 = (
             models.Book.objects.filter(author__name=self.a1.name)
             .prewhere(author_id=self.a1.id)
-            .order_by("name"),
-            [self.b1, self.b2],
+            .order_by("id")
         )
+        self.assertTrue(b1.id == self.b1.id and b2.id == self.b2.id)
 
     # clickhouse backend will generate suitable query, but clickhouse will raise exception.
     # clickhouse 23.11
@@ -64,12 +66,15 @@ def test_prewhere_agg(self):
                 )
             )
 
-    def test_prewhere_window(self):
-        with self.assertRaisesMessage(
-            NotSupportedError, "Window function is disallowed in the prewhere clause."
-        ):
-            list(
-                models.Book.objects.annotate(
-                    rank=Window(Rank(), partition_by="author", order_by="name")
-                ).prewhere(rank__gt=1)
-            )
+    if compat.dj_ge42:
+
+        def test_prewhere_window(self):
+            with self.assertRaisesMessage(
+                NotSupportedError,
+                "Window function is disallowed in the prewhere clause.",
+            ):
+                list(
+                    models.Book.objects.annotate(
+                        rank=Window(Rank(), partition_by="author", order_by="name")
+                    ).prewhere(rank__gt=1)
+                )